This invention relates generally to electrostatographic reproduction machines, and more particularly, to a fuser adapted to use high frequency field propagation providers to induce heating while bypassing thermal conducting interfaces.
In electrostatographic printing, commonly known as xerographic or printing or copying, an important process step is known as “fusing”. In the fusing step of the xerographic process, dry marking making material, such as toner, which has been placed in imagewise fashion on an imaging substrate, such as a sheet of paper, is subjected to heat and/or pressure in order to melt the otherwise fuse the toner permanently on the substrate. In this way, durable, non-smudging images are rendered on the substrates.
The most common design of a fusing apparatus as used in commercial printers includes two rolls, typically called a fuser roll and a pressure roll, forming a nip therebetween for the passage of the substrate therethrough. Typically, the fuser roll further includes, disposed on the interior thereof, one or more heating elements, which radiate heat in response to a current being passed therethrough. Various fuser roll systems include a heated fuser roller and a pressure roller to form a nip through which a receiving substrate can pass. The receiving substrate, before passing through the nip, contains previously deposited toner. The heated fuser roll in combination with the pressure roll acts to melt and press the previously deposited toner onto the receiving substrate. Various belt systems can also act to melt and press toner onto the receiving substrate. In both cases, the fusing of the toner particles generally takes place when the proper combination of heat, pressure, and contact time are provided.
However, due to various sizes in the thermal conducting interfaces, there is a tendency to develop gaps in thermal temperature uniformity across a belt fuser. To address these gaps in thermal uniformity various methods have address the issue by increase the thermal output of the heater. Such methods develop problems in that it may require decreases in throughput or set-point changes which require a large dead time. These process speed limitations with solid heater elements reduce the extendibility to design which require high throughput such as higher than 90 ppm.